[Re-thinking of "pelvirectal space"].

Before the "mesorectal" theory was proposed, the traditional anatomy believed that the "pelvirectal space" belonged to the anal canal and perirectal space, which was independent of the rectal structure, located on both sides of the rectum, above the levator ani, and below the peritoneal reflexion, and was composed of a large amount of fatty tissue filling. With the development of the theory of membrane anatomy and the clarification of the concept of "rectal mesentery", combined with the author's clinical experience, we found that the above-mentioned fat is actually the fat within the mesorectum, as well as the fat tissue of lateral lymph nodes (LLN) such as the internal iliac lymph nodes (No.263) and obturator lymph nodes (No.283) on both sides of the rectal mesentery, rather than the so-called fat tissue within the interstitial space. Therefore, the author believes that the pelvirectal space does not exist. In the anatomical location equivalent to the pelvic rectal space, there is the "superior levator ani space" based on the membrane anatomy theory. From the pelvirectal space to the superior levator anal space, it reflects our further understanding of the anatomy of the rectal mesentery.

Retroperitoneoscopy of the presacral space in horses: Surgical access and anatomy.

BACKGROUND: Surgical approaches to the equine rectum and perirectal area are described in the literature. However, surgeries in this region can be challenging. OBJECTIVE: To describe the surgical anatomy of the presacral space and to evaluate its access using a retroperitoneoscopic approach. STUDY DESIGN: Ex vivo experiment. METHODS: Preliminary dissections were performed in two cadavers to define the boundaries of the presacral space and to determine portal locations for the surgical approach. After that, nine cadavers were used for experimental presacral retroperitoneoscopic procedure in a standing position. Following retroperitoneoscopy, cadavers were dissected to confirm the anatomical structures observed during the endoscopic procedures, to control the location of each portal and to record iatrogenic trauma. RESULTS: The presacral space was bordered by the vertebral column from the ventral aspect of lumbosacral promontorium to the first coccygeal vertebra dorsally and by the presacral fascia and peritoneum ventrally. Lateral limits were composed of the sacrosciatic ligament and transversalis fascia. Cranial and caudal borders were composed of the peritoneum and coccygeal and levator ani muscles respectively. Retroperitoneoscopic portals were placed between the external anal sphincter and semimembranosus muscles and between the base of the tail and the external anal sphincter muscle through the anococcygeal fascia to enter the space by its caudal border. The retroperitoneal space was reached in all cases and the dorsal and lateral aspects of the rectum were visualised after creation of a working space. MAIN LIMITATIONS: Use of cadaver specimens do not permit to evaluate the tolerance in living animals and the surgical complications such as rectal damage, haemorrhage and infection. CONCLUSION: This study provides an anatomical description and surgical access of the presacral space with a minimal invasive approach. Retroperitoneoscopy allows access to the rectum and the dorsal aspect of the pelvis.

[Classification system of radical surgery for rectal cancer based on membrane anatomy].

Because the classification system of radical surgery for rectal cancer has not been established, it is impossible to select the appropriate surgical method according to the clinical stage of the tumor. In this paper, we explained the theory of " four fasciae and three spaces " of pelvic membrane anatomy and then combined this theory with the membrane anatomical basis of Querleu-Morrow classification for radical cervical cancer resection. Based on this theory and the membrane anatomy of Querleu-Morrow classification of radical cervical cancer resection, we proposed a new classification system of radical rectal cancer surgery based on membrane anatomy according to the lateral lymph node dissection range of the rectum. This system classifies the surgery into four types (ABCD) and defines corresponding subtypes based on whether the autonomic nerve was preserved. Among them, type A surgery is total mesorectal excision (TME) with urogenital fascia preservation, type B surgery is classical TME, type C surgery is extended TME, and type D surgery is lateral extended resection. This classification system unifies the anatomical terminology of the pelvic membrane, validates the feasibility of using the " four fasciae and three fascial spaces " theory to classify rectal cancer surgery, and lays the theoretical foundation for the future development of a unified and standardized classification of radical pelvic tumor surgery.

Classification system of radical surgery for rectal cancer based on membrane anatomy / 中华胃肠外科杂志

Because the classification system of radical surgery for rectal cancer has not been established, it is impossible to select the appropriate surgical method according to the clinical stage of the tumor. In this paper, we explained the theory of " four fasciae and three spaces " of pelvic membrane anatomy and then combined this theory with the membrane anatomical basis of Querleu-Morrow classification for radical cervical cancer resection. Based on this theory and the membrane anatomy of Querleu-Morrow classification of radical cervical cancer resection, we proposed a new classification system of radical rectal cancer surgery based on membrane anatomy according to the lateral lymph node dissection range of the rectum. This system classifies the surgery into four types (ABCD) and defines corresponding subtypes based on whether the autonomic nerve was preserved. Among them, type A surgery is total mesorectal excision (TME) with urogenital fascia preservation, type B surgery is classical TME, type C surgery is extended TME, and type D surgery is lateral extended resection. This classification system unifies the anatomical terminology of the pelvic membrane, validates the feasibility of using the " four fasciae and three fascial spaces " theory to classify rectal cancer surgery, and lays the theoretical foundation for the future development of a unified and standardized classification of radical pelvic tumor surgery.

[Cognition and reflection on the "lateral ligament of rectum"].

As total mesorectal excision (TME) for rectal cancer is widely carried out in China, lateral ligament of rectum, as an important anatomical structure of the lateral rectum with certain anatomical value and clinical significance, has been the focus of attention. In this paper, by comparing and analyzing the characteristics about ligaments of the abdomen and pelvis, reviewing the membrane anatomy and the theory of primitive gut rotation, and combining clinical observations and histological studies, the author came to a conclusion that lateral ligament of rectum does not exist, but is only a relatively dense space on the rectal side accompanied by numerous tiny nerve plexuses and small blood vessels penetrating through it.

[Anatomical observation and clinical significance of the prostatic part of neurovascular bundle in total mesorectal excision].

Objective: To observe the anatomical architecture of the prostatic part of the neurovascular bundle (NVB) in total mesorectal excision (TME). Methods: A descriptive cohort study and an anatomical observation study were carried out. A total of 38 male patients with rectal cancer who underwent TME in the Department of Colorectal Surgery at the affiliated Union hospital of Fujian Medical University between November 2013 and March 2015 were included. A total of 4 hemipelvis were examined at the Laboratory of Clinical Applied Anatomy, Fujian Medical University. The following outcomes were observed: 1) the clinical significance of bleeding of the prostatic part of NVB: surgical videos were reviewed and the incidence of bleeding was recorded. The urogenital function was assessed using the International Prostate Symptom Score (IPSS) and International Index of Erectile Function (IIEF) score. The correlation between prostatic part bleeding and postoperative urogenital function was evaluated. 2) anatomical observation: the vessels, nerve fibers, as well as their surrounding fatty tissue from the prostatic part were treated as a whole, namely, the fat pad of the prostatic part. The anatomical architecture of the prostatic part in the surgical videos was reviewed and interpreted with the cadaveric findings. Categorical variables were compared between groups using a Fisher exact probability. while continuous variables with skewed distribution were compared between groups using the Mann-Whiteny U test. Results: The median age of the included 38 patients was 57 years (range, 31-75), and the median tumor distance to the anal verge was 6 cm (range, 1-8). Of them, a total number of 21 (55.3%) patients had bleeding of the prostatic part of NVB (bleeding group), while the rest had not (17 cases, 44.7%, non-bleeding group). 1) the clinical significance of bleeding of the prostatic part of NVB. The urinary function significantly decreased in patients in the bleeding group according to IPSS score after the 3rd month and the 6rd month of the surgery [7 (0-16) vs. 2 (0-3), Z=-1.787, P=0.088; 2 (0-15) vs. 0 (0-2), Z=-2.270, P=0.028]. There was no difference regarding the IPSS score between the two groups after 1 year of the surgery (P>0.05). With a total of 23 patients with normal preoperative sexual activity included, 87.5% (7/8) of patients in the non-bleeding group can expect to return to their preoperative baseline, this incidence was significantly higher than that of only 40% (6/15) in the bleeding group (P=0.029). 2) anatomical observation: for cadaveric observation, the prostatic part of NVB was located in the narrow triangular space composed of anterolateral walls of the rectum, the posterolateral surface of the prostate and the medial surface of the levator ani musculature. The tiny vascular branches and nerve fibers from the prostatic part were hard to identify. The cavernosal nerves cannot reliably be distinguished from the neural supply to the prostate, rectum and levator ani. In the cross-section of levels of prostatic base and mid-prostate in cadaveric hemipelvis specimens, the boundary of the prostatic part fat pad was partly overlapped and merged with the boundary of the mesorectum. Intraoperative observation showed that the areas of overlap referred to the rectal branches from the prostatic part piercing the proper fascia to supply the mesorectum, which carried the largest tension and high risk of bleeding during circumferential dissection toward the perirectal plane. The ultrasonic scalpel was required to pre-coagulate the rectal branches at the point close to the proper fascia of the rectum to prevent bleeding. In the cross-section of the prostatic apex level, the prostatic part approached ventrally and its boundary was away from the boundary of the mesorectum. Conclusions: NVB prostatic part injury is one of the causes of urogenital dysfunction after TME. The nerve fibers from the prostatic part were tiny, and its functional zones cannot be distinguished during operation. Therein, the fat pad of the prostatic part should be protected as a whole. Understanding the morphology of the fat pad of the prostatic part provides invaluable surgical guidance to dissect this critical area. When dissecting around the anterolateral rectal wall, appropriate anti-traction tension should be maintained and the rectal branches from the prostatic part should be coagulated with an ultrasonic scalpel to prevent bleeding.

Is there a precise correlation between the lengths of the peritoneal reflection and the middle rectal valve?

Introduction: Pelvic anatomy remains a challenge, and thorough knowledge of its intricate landmarks has major clinical and surgical implications in several medical specialties. The peritoneal reflection is an important landmark in intraluminal surgery, rectal trauma, impalement, and rectal adenocarcinoma. Objectives: To investigate the correlation between the lengths of the middle rectal valve and of the peritoneal reflection determined with rigid sigmoidoscopy and to determine whether there are any differences in the location of the peritoneal reflection between the genders and in relation to body mass index (BMI) and parity. Design: We prospectively investigated the location of the middle rectal valve and of the peritoneal reflection via intraoperative rigid sigmoidoscopy in colorectal cancer patients undergoing elective colorectal surgery. Results: We evaluated 38 patients with a mean age of 55.5 years old (57.5% males) who underwent colorectal surgery at the coloproctology service of the Hospital Santa Marcelina, São Paulo, state of São Paulo, Brazil. There was substantial agreement between the lengths of the middle rectal valve and of the peritoneal reflection (Kappa = 0.66). In addition, the peritoneal reflection was significantly lower in overweight patients (p = 0.013 for women and p < 0.005 for men) and in women with > 2 vaginal deliveries (p = 0.009), but there was no significant difference in the length of the peritoneal reflection between genders (p = 0.32). Conclusion: There was substantial agreement between the lengths of the peritoneal reflection and of the middle rectal valve, and the peritoneal reflection was significantly lower in overweight patients and in women with more than two vaginal deliveries. (AU)

Cognition and reflection on the "lateral ligament of rectum" / 中华胃肠外科杂志

As total mesorectal excision (TME) for rectal cancer is widely carried out in China, lateral ligament of rectum, as an important anatomical structure of the lateral rectum with certain anatomical value and clinical significance, has been the focus of attention. In this paper, by comparing and analyzing the characteristics about ligaments of the abdomen and pelvis, reviewing the membrane anatomy and the theory of primitive gut rotation, and combining clinical observations and histological studies, the author came to a conclusion that lateral ligament of rectum does not exist, but is only a relatively dense space on the rectal side accompanied by numerous tiny nerve plexuses and small blood vessels penetrating through it.

Anatomical observation and clinical significance of the prostatic part of neurovascular bundle in total mesorectal excision / 中华胃肠外科杂志

Objective: To observe the anatomical architecture of the prostatic part of the neurovascular bundle (NVB) in total mesorectal excision (TME). Methods: A descriptive cohort study and an anatomical observation study were carried out. A total of 38 male patients with rectal cancer who underwent TME in the Department of Colorectal Surgery at the affiliated Union hospital of Fujian Medical University between November 2013 and March 2015 were included. A total of 4 hemipelvis were examined at the Laboratory of Clinical Applied Anatomy, Fujian Medical University. The following outcomes were observed: 1) the clinical significance of bleeding of the prostatic part of NVB: surgical videos were reviewed and the incidence of bleeding was recorded. The urogenital function was assessed using the International Prostate Symptom Score (IPSS) and International Index of Erectile Function (IIEF) score. The correlation between prostatic part bleeding and postoperative urogenital function was evaluated. 2) anatomical observation: the vessels, nerve fibers, as well as their surrounding fatty tissue from the prostatic part were treated as a whole, namely, the fat pad of the prostatic part. The anatomical architecture of the prostatic part in the surgical videos was reviewed and interpreted with the cadaveric findings. Categorical variables were compared between groups using a Fisher exact probability. while continuous variables with skewed distribution were compared between groups using the Mann-Whiteny U test. Results: The median age of the included 38 patients was 57 years (range, 31-75), and the median tumor distance to the anal verge was 6 cm (range, 1-8). Of them, a total number of 21 (55.3%) patients had bleeding of the prostatic part of NVB (bleeding group), while the rest had not (17 cases, 44.7%, non-bleeding group). 1) the clinical significance of bleeding of the prostatic part of NVB. The urinary function significantly decreased in patients in the bleeding group according to IPSS score after the 3rd month and the 6rd month of the surgery [7 (0-16) vs. 2 (0-3), Z=-1.787, P=0.088; 2 (0-15) vs. 0 (0-2), Z=-2.270, P=0.028]. There was no difference regarding the IPSS score between the two groups after 1 year of the surgery (P>0.05). With a total of 23 patients with normal preoperative sexual activity included, 87.5% (7/8) of patients in the non-bleeding group can expect to return to their preoperative baseline, this incidence was significantly higher than that of only 40% (6/15) in the bleeding group (P=0.029). 2) anatomical observation: for cadaveric observation, the prostatic part of NVB was located in the narrow triangular space composed of anterolateral walls of the rectum, the posterolateral surface of the prostate and the medial surface of the levator ani musculature. The tiny vascular branches and nerve fibers from the prostatic part were hard to identify. The cavernosal nerves cannot reliably be distinguished from the neural supply to the prostate, rectum and levator ani. In the cross-section of levels of prostatic base and mid-prostate in cadaveric hemipelvis specimens, the boundary of the prostatic part fat pad was partly overlapped and merged with the boundary of the mesorectum. Intraoperative observation showed that the areas of overlap referred to the rectal branches from the prostatic part piercing the proper fascia to supply the mesorectum, which carried the largest tension and high risk of bleeding during circumferential dissection toward the perirectal plane. The ultrasonic scalpel was required to pre-coagulate the rectal branches at the point close to the proper fascia of the rectum to prevent bleeding. In the cross-section of the prostatic apex level, the prostatic part approached ventrally and its boundary was away from the boundary of the mesorectum. Conclusions: NVB prostatic part injury is one of the causes of urogenital dysfunction after TME. The nerve fibers from the prostatic part were tiny, and its functional zones cannot be distinguished during operation. Therein, the fat pad of the prostatic part should be protected as a whole. Understanding the morphology of the fat pad of the prostatic part provides invaluable surgical guidance to dissect this critical area. When dissecting around the anterolateral rectal wall, appropriate anti-traction tension should be maintained and the rectal branches from the prostatic part should be coagulated with an ultrasonic scalpel to prevent bleeding.

Fascial Organisation and Lymphatic Systems Around the Pelvic Floor: A Literature Review.

This review summarises the anatomy and lymphatic systems around the pelvic floor. We investigated the lymphovascular network in the anorectal region, focusing on the hiatal ligament, which comprises smooth muscle fibres derived from the longitudinal muscle and connecting the anal canal and coccyx, and the endopelvic fascia, which seems to comprise collagen and elastic fibres. During rectal surgery, endopelvic fascia is recognized as a sheet of fascia covering the levator ani muscle. Endopelvic fascia is extensively attached to the smooth muscle fibres diverging from the longitudinal muscle of the rectum. Analysis of the lymphovascular network using submucosal India ink injection and indocyanine green fluorescence imaging suggests a functional lymphatic flow between rectal muscle fibres and hiatal ligament and endopelvic fascia. Precise analysis of the lymphatic systems of fascial organization around the pelvic floor may be useful in formulating therapeutic strategies for low rectal cancer.

Understanding the anatomy of the Denonvilliers fascia: review article / Compreendendo a anatomia da fáscia de Denonvilliers: artigo de revisão

Abstract The postoperative outcome of rectal cancer has been improved after the introduction of the principles of total mesorectal excision (TME). Total mesorectal excision includes resection of the diseased rectum and mesorectum with non-violated mesorectal fascia (en bloc resection). Dissection along themesorectal fascia through the principle of the "holy plane" minimizes injury of the autonomic nerves and increases the chance of preserving them. It is important to stick to the TME principle to avoid perforating the tumor; violating the mesorectal fascia, thus resulting in positive circumferential resection margin (CRM); or causing injury to the autonomic nerves, especially if the tumor is located anteriorly. Therefore, identifying the anterior plane of dissection during TME is important because it is related with the autonomic nerves (Denonvilliers fascia). Although there are many articles about the Denonvilliers fascia (DVF) or the anterior dissection plane, unfortunately, there is no consensus on its embryological origin, histology, and gross anatomy. In the present review article, I aim to delineate and describe the anatomy of the DVF inmore details based on a review of the literature, in order to provide insight for colorectal surgeons to better understand this anatomical feature and to provide the best care to their patients.

Resumo O resultado pós-operatório do câncer retal foi melhorado após a introdução dos princípios da excisão total do mesorreto (TME, na sigla em inglês). A excisão total do mesorreto inclui a ressecção do reto e do mesorreto afetados com fáscia mesorretal não violada (ressecção em bloco). A dissecção ao longo da fáscia mesorretal pelo princípio do "plano sagrado" minimiza a lesão dos nervos autônomos e aumenta a chance de preservá-los. É importante seguir o princípio da TME para evitar: a perfuração do tumor; a violação da fáscia mesorretal, resultando em margem de ressecção circunferencial (CRM) positiva; ou a lesão aos nervos autônomos, especialmente se o tumor estiver localizado anteriormente. Portanto, a identificação do plano anterior de dissecção durante a TME é importante, pois está relacionada comos nervos autonômicos (fáscia de Denonvilliers). Embora existammuitos artigos sobre a fáscia de Denonvilliers (DVF, na sigla em inglês) ou o plano de dissecção anterior, infelizmente não há consenso sobre sua origem embriológica, histologia e anatomia macroscópica. No presente artigo de revisão, retendo delinear e descrever a anatomia da DVF em mais detalhes com base em uma revisão da literatura, a fim de fornecer subsídios para os cirurgiões colorretais entenderemmelhor esta característica anatômica e fornecer o melhor cuidado para seus pacientes.

Surgical Anatomy of the Rectovaginal Space: Does a Standalone Rectovaginal Septum or Denonvilliers Fascia Exist in Women?

BACKGROUND: Below the anterior peritoneal reflection, the anterior rectal wall and mesorectum are separated from the posterior vaginal wall by a virtual rectovaginal space. In this space, the description of a specific and independent rectovaginal septum as a female counterpart of Denonvilliers fascia has been the subject of debate over the years. OBJECTIVE: The aim of this study is to perform an accurate anatomical study of the rectovaginal area in a cadaveric simulation model of total mesorectal excision to evaluate the possible structures and the dissection planes contained within the rectovaginal space. DESIGN AND SETTING: This is a cadaveric study performed at the University of Valencia. PATIENTS: The pelvises of 25 formalin-preserved female cadavers were dissected. All the included specimens were sectioned in a midsagittal plane, at the level of the middle axis of the anal canal. MAIN OUTCOME MEASURES: Careful and detailed dissection was performed to visualize the anatomical structures and potential dissection planes during anterior mesorectal dissection in cadavers. Histological sections were made of the posterior vaginal wall. RESULTS: The rectovaginal space contains loose areolar tissue that allows an easy dissection plane distally. A distinct and independent rectovaginal fascia or septum is not present. The existence of 3 layers fused together in the posterior vaginal wall can be identified more or less precisely because of their different coloration. The histological study confirms this macroscopic arrangement of the posterior vaginal wall in 3 layers: the mucosa, the muscular, and the adventitia. An independent rectovaginal septum can be generated only with a splitting of the adventitia. LIMITATIONS: The cadaveric pelvic specimens of the oldest donors might have had age-related degeneration. CONCLUSIONS: The present anatomical study has shown only a plane of loose areolar tissue between the rectal and vaginal wall. We can conclude that there is no independent fascia or septum in the rectovaginal space. See Video Abstract at http://links.lww.com/DCR/B456. ANATOMÍA QUIRÚRGICA DEL ESPACIO RECTOVAGINAL: ¿EXISTE UN TABIQUE RECTOVAGINAL INDEPENDIENTE O UNA FASCIA DE DENONVILLIERS EN LAS MUJERES: Debajo del reflejo peritoneal anterior, la pared rectal anterior y el mesorrecto están separados de la pared vaginal posterior por un espacio rectovaginal virtual. En este espacio, la descripción de un tabique rectovaginal independiente específico como contraparte femenina de la fascia de Denonvilliers ha sido objeto de debate a lo largo de los años.Realizar un estudio anatómico preciso del área rectovaginal en un modelo de simulación cadavérica de escisión mesorrectal total, con el fin de evaluar las posibles estructuras y los planos de disección contenidos en el espacio rectovaginal.estudio cadavérico realizado en la Universidad de Valencia.Se disecaron las pelvis de 25 cadáveres femeninos conservados en formalina. Todas las muestras incluidas fueron seccionadas en un plano medio sagital, a la altura del eje medio del canal anal.Se llevó a cabo una disección cuidadosa y detallada para visualizar las estructuras anatómicas y los posibles planos de disección durante la disección mesorrectal anterior en cadáveres. Se realizaron cortes histológicos de la pared vaginal posterior.El espacio rectovaginal contiene tejido areolar laxo que permite un plano de disección fácil distalmente. No hay fascia o tabique rectovaginal distinto e independiente. La existencia de tres capas fusionadas en la pared vaginal posterior puede identificarse con mayor o menor precisión debido a su diferente coloración. El estudio histológico confirma esta disposición macroscópica de la pared vaginal posterior en tres capas: la mucosa, la muscular y la adventicia. Un tabique rectovaginal independiente solo se puede generar con una división de la adventicia.Las muestras pélvicas de cadáveres de los donantes más antiguos pueden haber tenido degeneración relacionada con la edad.El estudio anatómico actual solo ha mostrado un plano de tejido areolar laxo entre la pared rectal y vaginal. Podemos concluir que no hay fascia o tabique independiente en el espacio rectovaginal. Consulte Video Resumen en http://links.lww.com/DCR/B456. (Traducción-Dr. Adrian Ortega).

Conversion and validation of rectal constraints for prostate carcinoma receiving hypofractionated carbon-ion radiotherapy with a local effect model.

BACKGROUND: The study objective was to establish the local effect model (LEM) rectum constraints for 12-, 8-, and 4-fraction carbon-ion radiotherapy (CIRT) in patients with localized prostate carcinoma (PCA) using microdosimetric kinetic model (MKM)-defined and LEM-defined constraints for 16-fraction CIRT. METHODS: We analyzed 40 patients with PCA who received 16- or 12-fraction CIRT at our center. Linear-quadratic (LQ) and RBE-conversion models were employed to convert the constraints into various fractionations and biophysical models. Based on them, the MKM LQ strategy converted MKM rectum constraints for 16-fraction CIRT to 12-, 8-, and 4-fraction CIRT using the LQ model. Then, MKM constraints were converted to LEM using the RBE-conversion model. Meanwhile the LEM LQ strategy converted MKM rectum constraints for 16-fraction CIRT to LEM using the RBE-conversion model. Then, LEM constraints were converted from 16-fraction constraints to the rectum constraints for 12-, 8-, and 4-fraction CIRT using the LQ model. The LEM constraints for 16- and 12-fraction CIRT were evaluated using rectum doses and clinical follow-up. To adapt them for the MKM LQ strategy, CNAO LEM constraints were first converted to MKM constraints using the RBE-conversion model. RESULTS: The NIRS (i.e. DMKM|v, V-20%, 10%, 5%, and 0%) and CNAO rectum constraints (i.e. DLEM|v, V-10 cc, 5 cc, and 1 cc) were converted for 12-fraction CIRT using the MKM LQ strategy to LEM 37.60, 49.74, 55.27, and 58.01 Gy (RBE), and 45.97, 51.70, and 55.97 Gy (RBE), and using the LEM LQ strategy to 39.55, 53.08, 58.91, and 61.73 Gy (RBE), and 49.14, 55.30, and 59.69 Gy (RBE). We also established LEM constraints for 8- and 4-fraction CIRT. The 10-patient RBE-conversion model was comparable to 30-patient model. Eight patients who received 16-fraction CIRT exceeded the corresponding rectum constraints; the others were within the constraints. After a median follow-up of 10.8 months (7.1-20.8), No ≥ G1 late rectum toxicities were observed. CONCLUSIONS: The LEM rectum constraints from the MKM LQ strategy were more conservative and might serve as the reference for hypofractionated CIRT. However, Long-term follow-up plus additional patients is necessary.

Dosimetric impact of rectum and bladder anatomy and intrafractional prostate motion on hypofractionated prostate radiation therapy.

OBJECTIVE: The objective of this study was to evaluate the dosimetric impact on hypofractionated prostate radiation therapy of two geometric uncertainty sources: rectum and bladder filling and intrafractional prostate motion. MATERIALS AND METHODS: This prospective study included 544 images (375 pre-treatment cone-beam CT [CBCT] and 169 post-treatment CBCT) from 15 prostate adenocarcinoma patients. We recalculated the dose on each pre-treatment CBCT once the positioning errors were corrected. We also recalculated two dose distributions on each post-treatment CBCT, either using or not intrafractional motion correction. A correlation analysis was performed between CBCT-based dose and rectum and bladder filling as well as intrafraction prostate displacements. RESULTS: No significant differences were found between administered and planned rectal doses. However, we observed an increase in bladder dose due to a lower bladder filling in 66% of treatment fractions. These differences were reduced at the end of the fraction since the lower bladder volume was compensated by the filling during the treatment session. A statistically significant reduction in target volume coverage was observed in 27% of treatment sessions and was correlated with intrafractional prostate motion in sagittal plane > 4 mm. CONCLUSIONS: A better control of bladder filling is recommended to minimize the number of fractions in which the bladder volume is lower than planned. Fiducial mark tracking with a displacement threshold of 5 mm in any direction is recommended to ensure that the prescribed dose criteria are met.

Colorectal dimensions in the general population: impact of age and gender.

PURPOSE: Constipation is among the most common gastrointestinal disorders, although, there is no generally accepted objective diagnostic criteria thereof. It has been proposed that colorectal dimensions assessed with Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) may support the diagnosis, but normative data are lacking. The aim of this study was to describe colorectal dimensions in a sample of the general population and to investigate whether the dimensions were under influence by age and gender. METHODS: The maximum diameters and cross-sectional areas of the ascending colon, descending colon and rectum were determined from 119 CT scans of trauma patients (age groups from 15 to 70 years, 84 men and 35 women). A regression model was applied to explore the impact of age and gender on colorectal dimensions. RESULTS: Overall, great variations were found for all colorectal diameters and cross-sectional areas (median diameter (5% percentiles; 95% percentiles): ascending 46 (26; 63) mm; descending 29 (16; 48) mm; rectum 39 (22; 67) mm. Women had larger rectal cross-sectional areas, reflecting more rectal content, compared to men (p = 0.003). Age did not affect colorectal diameters or cross-sectional areas (all p > 0.10). CONCLUSION: Great variations of colorectal dimensions were found. Larger rectal cross-sectional areas in women could likely reflect the fact that women have increased prevalence of constipation. Future studies should take gender into consideration when evaluating colorectal dimensions.

[Three-dimensional MRI reconstruction research on the anatomical relationship among uterosacral ligament and ureter or rectum in pelvic organ prolapse patients].

Objective: To study the anatomical relationship among uterosacral ligament and ureter or rectum by using MRI three-dimensional reconstruction model in pelvic organ prolapse (POP) patients. Methods: According to the research standard, 67 POP patients were enrolled, who accepted pelvic MRI before surgery in Nanfang Hospital, Southern Medical University during May 2015 to March 2020. Three-dimensional model of uterosacral ligament was reconstructed. The intersection point of the fitting curve of uterosacral ligament and ischial spine level marked point P0, every 1 cm increasing from P0 towards the sacrum marked points P1, P2, and P3. Distances were measured between rectum or ureter to uterosacral ligament respectively at the P0-P3 horizontal levels. Results: (1) The distances between the left ureter and the left uterosacral ligament were (15.45±7.46) to (19.31±11.38) mm, and the distances between the right ureter and the right uterosacral ligament were (13.77±8.16) to (14.78±9.18) mm. At the P1 horizontal level ureters were the closest to uterosacral ligaments, and the right ureter was the closest to right uterosacral ligament [(13.45±9.34) mm] at P2 horizontal level in severe POP group. The farthest distance presented at the P3 horizontal level between bilateral ureters and uterosacral ligaments. (2) At the P0 horizontal level, the rectum was the closest to the bilateral uterosacral ligaments [left: (20.62±9.99) mm, right: (16.82±9.63) mm; P=0.026], and the rectum was closer to the right uterosacral ligament. There were no significant differences in the distance between rectum and bilateral uterosacral ligaments in mild POP group (P>0.05), and the results of severe POP group also showed the rectum was closer to the right uterosacral ligament [(15.64±10.31) mm at P0 horizontal level]. Conclusions: Right ureter and rectum are closer to the right uterosacral ligament. Gynecologists should pay more attention to avoid damaging the right ureter and rectum during the operation of the right uterosacral ligament in POP patients.

The Sphincter of O'Beirne-Part 2: Report of a Case of Chronic Constipation with Autonomous Dyssynergia.

BACKGROUND: Chronic constipation can have one or more of many etiologies, and a diagnosis based on symptoms is not sufficient as a basis for treatment, in particular surgery. AIM: To investigate the cause of chronic constipation in a patient with complete absence of spontaneous bowel movements. METHODS: High-resolution colonic manometry was performed to assess motor functions of the colon, rectum, the sphincter of O'Beirne and the anal sphincters. RESULTS: Normal colonic motor patterns were observed, even at baseline, but a prominent high-pressure zone at the rectosigmoid junction, the sphincter of O'Beirne, was consistently present. In response to high-amplitude propagating pressure waves (HAPWs) that were not consciously perceived, the sphincter and the anal sphincters would not relax and paradoxically contract, identified as autonomous dyssynergia. Rectal bisacodyl evoked marked HAPW activity with complete relaxation of the sphincter of O'Beirne and the anal sphincters, indicating that all neural pathways to generate the coloanal reflex were intact but had low sensitivity to physiological stimuli. A retrograde propagating cyclic motor pattern initiated at the sphincter of O'Beirne, likely contributing to failure of content to move into the rectum. CONCLUSIONS: Chronic constipation without the presence of spontaneous bowel movements can be associated with normal colonic motor patterns but a highly exaggerated pressure at the rectosigmoid junction: the sphincter of O'Beirne, and failure of this sphincter and the anal sphincters to relax associated with propulsive motor patterns. The sphincter of O'Beirne can be an important part of the pathophysiology of chronic constipation.

The Sphincter of O'Beirne - Part 1: Study of 18 Normal Subjects.

BACKGROUND: Gastroenterologists have ignored or emphasized the importance of the rectosigmoid junction in continence or constipation on and off for 200 years. Here, we revisit its significance using high-resolution colonic manometry. METHODS: Manometry, using an 84-channel water-perfused catheter, was performed in 18 healthy volunteers. RESULTS: The rectosigmoid junction registers as an intermittent pressure band of 26.2 ± 7.2 mmHg, or intermittent phasic transient pressure increases at a dominant frequency of 3 cpm and an amplitude of 28.6 ± 8.6 mmHg; or a combination of tone and transient pressures, at a single sensor, 10-17 cm above the anal verge. Features are its relaxation or contraction in concert with relaxation or contraction of the anal sphincters when a motor pattern such as a high-amplitude propagating pressure wave or a simultaneous pressure wave comes down, indicating that such pressure increases or decreases at the rectosigmoid junction are part of neurally driven programs. We show that the junction is a site where motor patterns end, or where they start; e.g. retrogradely propagating cyclic motor patterns emerge from the junction. CONCLUSIONS: The rectosigmoid junction is a functional sphincter that should be referred to as the sphincter of O'Beirne; it is part of the "braking mechanism," contributing to continence by keeping content away from the rectum. In an accompanying case report, we show that its excessive presence in a patient with severe constipation can be a primary pathophysiology.